rgrp.c 35.3 KB
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/*
 * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
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 * Copyright (C) 2004-2006 Red Hat, Inc.  All rights reserved.
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 *
 * This copyrighted material is made available to anyone wishing to use,
 * modify, copy, or redistribute it subject to the terms and conditions
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 * of the GNU General Public License version 2.
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 */

#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/completion.h>
#include <linux/buffer_head.h>
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#include <linux/fs.h>
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#include <linux/gfs2_ondisk.h>
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#include <linux/lm_interface.h>
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#include "gfs2.h"
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#include "incore.h"
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#include "glock.h"
#include "glops.h"
#include "lops.h"
#include "meta_io.h"
#include "quota.h"
#include "rgrp.h"
#include "super.h"
#include "trans.h"
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#include "ops_file.h"
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#include "util.h"
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#define BFITNOENT ((u32)~0)
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/*
 * These routines are used by the resource group routines (rgrp.c)
 * to keep track of block allocation.  Each block is represented by two
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 * bits.  So, each byte represents GFS2_NBBY (i.e. 4) blocks.
 *
 * 0 = Free
 * 1 = Used (not metadata)
 * 2 = Unlinked (still in use) inode
 * 3 = Used (metadata)
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 */

static const char valid_change[16] = {
	        /* current */
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	/* n */ 0, 1, 1, 1,
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	/* e */ 1, 0, 0, 0,
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	/* w */ 0, 0, 0, 1,
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	        1, 0, 0, 0
};

/**
 * gfs2_setbit - Set a bit in the bitmaps
 * @buffer: the buffer that holds the bitmaps
 * @buflen: the length (in bytes) of the buffer
 * @block: the block to set
 * @new_state: the new state of the block
 *
 */

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static void gfs2_setbit(struct gfs2_rgrpd *rgd, unsigned char *buffer,
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			unsigned int buflen, u32 block,
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			unsigned char new_state)
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{
	unsigned char *byte, *end, cur_state;
	unsigned int bit;

	byte = buffer + (block / GFS2_NBBY);
	bit = (block % GFS2_NBBY) * GFS2_BIT_SIZE;
	end = buffer + buflen;

	gfs2_assert(rgd->rd_sbd, byte < end);

	cur_state = (*byte >> bit) & GFS2_BIT_MASK;

	if (valid_change[new_state * 4 + cur_state]) {
		*byte ^= cur_state << bit;
		*byte |= new_state << bit;
	} else
		gfs2_consist_rgrpd(rgd);
}

/**
 * gfs2_testbit - test a bit in the bitmaps
 * @buffer: the buffer that holds the bitmaps
 * @buflen: the length (in bytes) of the buffer
 * @block: the block to read
 *
 */

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static unsigned char gfs2_testbit(struct gfs2_rgrpd *rgd, unsigned char *buffer,
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				  unsigned int buflen, u32 block)
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{
	unsigned char *byte, *end, cur_state;
	unsigned int bit;

	byte = buffer + (block / GFS2_NBBY);
	bit = (block % GFS2_NBBY) * GFS2_BIT_SIZE;
	end = buffer + buflen;

	gfs2_assert(rgd->rd_sbd, byte < end);

	cur_state = (*byte >> bit) & GFS2_BIT_MASK;

	return cur_state;
}

/**
 * gfs2_bitfit - Search an rgrp's bitmap buffer to find a bit-pair representing
 *       a block in a given allocation state.
 * @buffer: the buffer that holds the bitmaps
 * @buflen: the length (in bytes) of the buffer
 * @goal: start search at this block's bit-pair (within @buffer)
 * @old_state: GFS2_BLKST_XXX the state of the block we're looking for;
 *       bit 0 = alloc(1)/free(0), bit 1 = meta(1)/data(0)
 *
 * Scope of @goal and returned block number is only within this bitmap buffer,
 * not entire rgrp or filesystem.  @buffer will be offset from the actual
 * beginning of a bitmap block buffer, skipping any header structures.
 *
 * Return: the block number (bitmap buffer scope) that was found
 */

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static u32 gfs2_bitfit(struct gfs2_rgrpd *rgd, unsigned char *buffer,
			    unsigned int buflen, u32 goal,
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			    unsigned char old_state)
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{
	unsigned char *byte, *end, alloc;
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	u32 blk = goal;
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	unsigned int bit;

	byte = buffer + (goal / GFS2_NBBY);
	bit = (goal % GFS2_NBBY) * GFS2_BIT_SIZE;
	end = buffer + buflen;
	alloc = (old_state & 1) ? 0 : 0x55;

	while (byte < end) {
		if ((*byte & 0x55) == alloc) {
			blk += (8 - bit) >> 1;

			bit = 0;
			byte++;

			continue;
		}

		if (((*byte >> bit) & GFS2_BIT_MASK) == old_state)
			return blk;

		bit += GFS2_BIT_SIZE;
		if (bit >= 8) {
			bit = 0;
			byte++;
		}

		blk++;
	}

	return BFITNOENT;
}

/**
 * gfs2_bitcount - count the number of bits in a certain state
 * @buffer: the buffer that holds the bitmaps
 * @buflen: the length (in bytes) of the buffer
 * @state: the state of the block we're looking for
 *
 * Returns: The number of bits
 */

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static u32 gfs2_bitcount(struct gfs2_rgrpd *rgd, unsigned char *buffer,
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			      unsigned int buflen, unsigned char state)
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{
	unsigned char *byte = buffer;
	unsigned char *end = buffer + buflen;
	unsigned char state1 = state << 2;
	unsigned char state2 = state << 4;
	unsigned char state3 = state << 6;
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	u32 count = 0;
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	for (; byte < end; byte++) {
		if (((*byte) & 0x03) == state)
			count++;
		if (((*byte) & 0x0C) == state1)
			count++;
		if (((*byte) & 0x30) == state2)
			count++;
		if (((*byte) & 0xC0) == state3)
			count++;
	}

	return count;
}

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/**
 * gfs2_rgrp_verify - Verify that a resource group is consistent
 * @sdp: the filesystem
 * @rgd: the rgrp
 *
 */

void gfs2_rgrp_verify(struct gfs2_rgrpd *rgd)
{
	struct gfs2_sbd *sdp = rgd->rd_sbd;
	struct gfs2_bitmap *bi = NULL;
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	u32 length = rgd->rd_ri.ri_length;
	u32 count[4], tmp;
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	int buf, x;

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	memset(count, 0, 4 * sizeof(u32));
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	/* Count # blocks in each of 4 possible allocation states */
	for (buf = 0; buf < length; buf++) {
		bi = rgd->rd_bits + buf;
		for (x = 0; x < 4; x++)
			count[x] += gfs2_bitcount(rgd,
						  bi->bi_bh->b_data +
						  bi->bi_offset,
						  bi->bi_len, x);
	}

	if (count[0] != rgd->rd_rg.rg_free) {
		if (gfs2_consist_rgrpd(rgd))
			fs_err(sdp, "free data mismatch:  %u != %u\n",
			       count[0], rgd->rd_rg.rg_free);
		return;
	}

	tmp = rgd->rd_ri.ri_data -
		rgd->rd_rg.rg_free -
		rgd->rd_rg.rg_dinodes;
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	if (count[1] + count[2] != tmp) {
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		if (gfs2_consist_rgrpd(rgd))
			fs_err(sdp, "used data mismatch:  %u != %u\n",
			       count[1], tmp);
		return;
	}

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	if (count[3] != rgd->rd_rg.rg_dinodes) {
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		if (gfs2_consist_rgrpd(rgd))
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			fs_err(sdp, "used metadata mismatch:  %u != %u\n",
			       count[3], rgd->rd_rg.rg_dinodes);
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		return;
	}

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	if (count[2] > count[3]) {
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		if (gfs2_consist_rgrpd(rgd))
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			fs_err(sdp, "unlinked inodes > inodes:  %u\n",
			       count[2]);
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		return;
	}
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}

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static inline int rgrp_contains_block(struct gfs2_rindex *ri, u64 block)
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{
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	u64 first = ri->ri_data0;
	u64 last = first + ri->ri_data;
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	return first <= block && block < last;
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}

/**
 * gfs2_blk2rgrpd - Find resource group for a given data/meta block number
 * @sdp: The GFS2 superblock
 * @n: The data block number
 *
 * Returns: The resource group, or NULL if not found
 */

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struct gfs2_rgrpd *gfs2_blk2rgrpd(struct gfs2_sbd *sdp, u64 blk)
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{
	struct gfs2_rgrpd *rgd;

	spin_lock(&sdp->sd_rindex_spin);

	list_for_each_entry(rgd, &sdp->sd_rindex_mru_list, rd_list_mru) {
		if (rgrp_contains_block(&rgd->rd_ri, blk)) {
			list_move(&rgd->rd_list_mru, &sdp->sd_rindex_mru_list);
			spin_unlock(&sdp->sd_rindex_spin);
			return rgd;
		}
	}

	spin_unlock(&sdp->sd_rindex_spin);

	return NULL;
}

/**
 * gfs2_rgrpd_get_first - get the first Resource Group in the filesystem
 * @sdp: The GFS2 superblock
 *
 * Returns: The first rgrp in the filesystem
 */

struct gfs2_rgrpd *gfs2_rgrpd_get_first(struct gfs2_sbd *sdp)
{
	gfs2_assert(sdp, !list_empty(&sdp->sd_rindex_list));
	return list_entry(sdp->sd_rindex_list.next, struct gfs2_rgrpd, rd_list);
}

/**
 * gfs2_rgrpd_get_next - get the next RG
 * @rgd: A RG
 *
 * Returns: The next rgrp
 */

struct gfs2_rgrpd *gfs2_rgrpd_get_next(struct gfs2_rgrpd *rgd)
{
	if (rgd->rd_list.next == &rgd->rd_sbd->sd_rindex_list)
		return NULL;
	return list_entry(rgd->rd_list.next, struct gfs2_rgrpd, rd_list);
}

static void clear_rgrpdi(struct gfs2_sbd *sdp)
{
	struct list_head *head;
	struct gfs2_rgrpd *rgd;
	struct gfs2_glock *gl;

	spin_lock(&sdp->sd_rindex_spin);
	sdp->sd_rindex_forward = NULL;
	head = &sdp->sd_rindex_recent_list;
	while (!list_empty(head)) {
		rgd = list_entry(head->next, struct gfs2_rgrpd, rd_recent);
		list_del(&rgd->rd_recent);
	}
	spin_unlock(&sdp->sd_rindex_spin);

	head = &sdp->sd_rindex_list;
	while (!list_empty(head)) {
		rgd = list_entry(head->next, struct gfs2_rgrpd, rd_list);
		gl = rgd->rd_gl;

		list_del(&rgd->rd_list);
		list_del(&rgd->rd_list_mru);

		if (gl) {
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			gl->gl_object = NULL;
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			gfs2_glock_put(gl);
		}

		kfree(rgd->rd_bits);
		kfree(rgd);
	}
}

void gfs2_clear_rgrpd(struct gfs2_sbd *sdp)
{
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	mutex_lock(&sdp->sd_rindex_mutex);
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	clear_rgrpdi(sdp);
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	mutex_unlock(&sdp->sd_rindex_mutex);
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}

/**
 * gfs2_compute_bitstructs - Compute the bitmap sizes
 * @rgd: The resource group descriptor
 *
 * Calculates bitmap descriptors, one for each block that contains bitmap data
 *
 * Returns: errno
 */

static int compute_bitstructs(struct gfs2_rgrpd *rgd)
{
	struct gfs2_sbd *sdp = rgd->rd_sbd;
	struct gfs2_bitmap *bi;
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	u32 length = rgd->rd_ri.ri_length; /* # blocks in hdr & bitmap */
	u32 bytes_left, bytes;
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	int x;

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	if (!length)
		return -EINVAL;

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	rgd->rd_bits = kcalloc(length, sizeof(struct gfs2_bitmap), GFP_NOFS);
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	if (!rgd->rd_bits)
		return -ENOMEM;

	bytes_left = rgd->rd_ri.ri_bitbytes;

	for (x = 0; x < length; x++) {
		bi = rgd->rd_bits + x;

		/* small rgrp; bitmap stored completely in header block */
		if (length == 1) {
			bytes = bytes_left;
			bi->bi_offset = sizeof(struct gfs2_rgrp);
			bi->bi_start = 0;
			bi->bi_len = bytes;
		/* header block */
		} else if (x == 0) {
			bytes = sdp->sd_sb.sb_bsize - sizeof(struct gfs2_rgrp);
			bi->bi_offset = sizeof(struct gfs2_rgrp);
			bi->bi_start = 0;
			bi->bi_len = bytes;
		/* last block */
		} else if (x + 1 == length) {
			bytes = bytes_left;
			bi->bi_offset = sizeof(struct gfs2_meta_header);
			bi->bi_start = rgd->rd_ri.ri_bitbytes - bytes_left;
			bi->bi_len = bytes;
		/* other blocks */
		} else {
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			bytes = sdp->sd_sb.sb_bsize -
				sizeof(struct gfs2_meta_header);
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			bi->bi_offset = sizeof(struct gfs2_meta_header);
			bi->bi_start = rgd->rd_ri.ri_bitbytes - bytes_left;
			bi->bi_len = bytes;
		}

		bytes_left -= bytes;
	}

	if (bytes_left) {
		gfs2_consist_rgrpd(rgd);
		return -EIO;
	}
	bi = rgd->rd_bits + (length - 1);
	if ((bi->bi_start + bi->bi_len) * GFS2_NBBY != rgd->rd_ri.ri_data) {
		if (gfs2_consist_rgrpd(rgd)) {
			gfs2_rindex_print(&rgd->rd_ri);
			fs_err(sdp, "start=%u len=%u offset=%u\n",
			       bi->bi_start, bi->bi_len, bi->bi_offset);
		}
		return -EIO;
	}

	return 0;
}

/**
 * gfs2_ri_update - Pull in a new resource index from the disk
 * @gl: The glock covering the rindex inode
 *
 * Returns: 0 on successful update, error code otherwise
 */

static int gfs2_ri_update(struct gfs2_inode *ip)
{
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	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
	struct inode *inode = &ip->i_inode;
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	struct gfs2_rgrpd *rgd;
	char buf[sizeof(struct gfs2_rindex)];
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	struct file_ra_state ra_state;
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	u64 junk = ip->i_di.di_size;
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	int error;

	if (do_div(junk, sizeof(struct gfs2_rindex))) {
		gfs2_consist_inode(ip);
		return -EIO;
	}

	clear_rgrpdi(sdp);

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	file_ra_state_init(&ra_state, inode->i_mapping);
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	for (sdp->sd_rgrps = 0;; sdp->sd_rgrps++) {
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		loff_t pos = sdp->sd_rgrps * sizeof(struct gfs2_rindex);
		error = gfs2_internal_read(ip, &ra_state, buf, &pos,
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					    sizeof(struct gfs2_rindex));
		if (!error)
			break;
		if (error != sizeof(struct gfs2_rindex)) {
			if (error > 0)
				error = -EIO;
			goto fail;
		}

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		rgd = kzalloc(sizeof(struct gfs2_rgrpd), GFP_NOFS);
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		error = -ENOMEM;
		if (!rgd)
			goto fail;

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		mutex_init(&rgd->rd_mutex);
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		lops_init_le(&rgd->rd_le, &gfs2_rg_lops);
		rgd->rd_sbd = sdp;

		list_add_tail(&rgd->rd_list, &sdp->sd_rindex_list);
		list_add_tail(&rgd->rd_list_mru, &sdp->sd_rindex_mru_list);

		gfs2_rindex_in(&rgd->rd_ri, buf);
		error = compute_bitstructs(rgd);
		if (error)
			goto fail;

		error = gfs2_glock_get(sdp, rgd->rd_ri.ri_addr,
				       &gfs2_rgrp_glops, CREATE, &rgd->rd_gl);
		if (error)
			goto fail;

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		rgd->rd_gl->gl_object = rgd;
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		rgd->rd_rg_vn = rgd->rd_gl->gl_vn - 1;
	}

	sdp->sd_rindex_vn = ip->i_gl->gl_vn;
	return 0;

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fail:
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	clear_rgrpdi(sdp);
	return error;
}

/**
 * gfs2_rindex_hold - Grab a lock on the rindex
 * @sdp: The GFS2 superblock
 * @ri_gh: the glock holder
 *
 * We grab a lock on the rindex inode to make sure that it doesn't
 * change whilst we are performing an operation. We keep this lock
 * for quite long periods of time compared to other locks. This
 * doesn't matter, since it is shared and it is very, very rarely
 * accessed in the exclusive mode (i.e. only when expanding the filesystem).
 *
 * This makes sure that we're using the latest copy of the resource index
 * special file, which might have been updated if someone expanded the
 * filesystem (via gfs2_grow utility), which adds new resource groups.
 *
 * Returns: 0 on success, error code otherwise
 */

int gfs2_rindex_hold(struct gfs2_sbd *sdp, struct gfs2_holder *ri_gh)
{
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	struct gfs2_inode *ip = GFS2_I(sdp->sd_rindex);
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	struct gfs2_glock *gl = ip->i_gl;
	int error;

	error = gfs2_glock_nq_init(gl, LM_ST_SHARED, 0, ri_gh);
	if (error)
		return error;

	/* Read new copy from disk if we don't have the latest */
	if (sdp->sd_rindex_vn != gl->gl_vn) {
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		mutex_lock(&sdp->sd_rindex_mutex);
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		if (sdp->sd_rindex_vn != gl->gl_vn) {
			error = gfs2_ri_update(ip);
			if (error)
				gfs2_glock_dq_uninit(ri_gh);
		}
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		mutex_unlock(&sdp->sd_rindex_mutex);
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	}

	return error;
}

/**
 * gfs2_rgrp_bh_get - Read in a RG's header and bitmaps
 * @rgd: the struct gfs2_rgrpd describing the RG to read in
 *
 * Read in all of a Resource Group's header and bitmap blocks.
 * Caller must eventually call gfs2_rgrp_relse() to free the bitmaps.
 *
 * Returns: errno
 */

int gfs2_rgrp_bh_get(struct gfs2_rgrpd *rgd)
{
	struct gfs2_sbd *sdp = rgd->rd_sbd;
	struct gfs2_glock *gl = rgd->rd_gl;
	unsigned int length = rgd->rd_ri.ri_length;
	struct gfs2_bitmap *bi;
	unsigned int x, y;
	int error;

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	mutex_lock(&rgd->rd_mutex);
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	spin_lock(&sdp->sd_rindex_spin);
	if (rgd->rd_bh_count) {
		rgd->rd_bh_count++;
		spin_unlock(&sdp->sd_rindex_spin);
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		mutex_unlock(&rgd->rd_mutex);
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		return 0;
	}
	spin_unlock(&sdp->sd_rindex_spin);

	for (x = 0; x < length; x++) {
		bi = rgd->rd_bits + x;
		error = gfs2_meta_read(gl, rgd->rd_ri.ri_addr + x, DIO_START,
				       &bi->bi_bh);
		if (error)
			goto fail;
	}

	for (y = length; y--;) {
		bi = rgd->rd_bits + y;
		error = gfs2_meta_reread(sdp, bi->bi_bh, DIO_WAIT);
		if (error)
			goto fail;
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		if (gfs2_metatype_check(sdp, bi->bi_bh, y ? GFS2_METATYPE_RB :
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					      GFS2_METATYPE_RG)) {
			error = -EIO;
			goto fail;
		}
	}

	if (rgd->rd_rg_vn != gl->gl_vn) {
		gfs2_rgrp_in(&rgd->rd_rg, (rgd->rd_bits[0].bi_bh)->b_data);
		rgd->rd_rg_vn = gl->gl_vn;
	}

	spin_lock(&sdp->sd_rindex_spin);
	rgd->rd_free_clone = rgd->rd_rg.rg_free;
	rgd->rd_bh_count++;
	spin_unlock(&sdp->sd_rindex_spin);

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	mutex_unlock(&rgd->rd_mutex);
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	return 0;

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	while (x--) {
		bi = rgd->rd_bits + x;
		brelse(bi->bi_bh);
		bi->bi_bh = NULL;
		gfs2_assert_warn(sdp, !bi->bi_clone);
	}
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	mutex_unlock(&rgd->rd_mutex);
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	return error;
}

void gfs2_rgrp_bh_hold(struct gfs2_rgrpd *rgd)
{
	struct gfs2_sbd *sdp = rgd->rd_sbd;

	spin_lock(&sdp->sd_rindex_spin);
	gfs2_assert_warn(rgd->rd_sbd, rgd->rd_bh_count);
	rgd->rd_bh_count++;
	spin_unlock(&sdp->sd_rindex_spin);
}

/**
 * gfs2_rgrp_bh_put - Release RG bitmaps read in with gfs2_rgrp_bh_get()
 * @rgd: the struct gfs2_rgrpd describing the RG to read in
 *
 */

void gfs2_rgrp_bh_put(struct gfs2_rgrpd *rgd)
{
	struct gfs2_sbd *sdp = rgd->rd_sbd;
	int x, length = rgd->rd_ri.ri_length;

	spin_lock(&sdp->sd_rindex_spin);
	gfs2_assert_warn(rgd->rd_sbd, rgd->rd_bh_count);
	if (--rgd->rd_bh_count) {
		spin_unlock(&sdp->sd_rindex_spin);
		return;
	}

	for (x = 0; x < length; x++) {
		struct gfs2_bitmap *bi = rgd->rd_bits + x;
		kfree(bi->bi_clone);
		bi->bi_clone = NULL;
		brelse(bi->bi_bh);
		bi->bi_bh = NULL;
	}

	spin_unlock(&sdp->sd_rindex_spin);
}

void gfs2_rgrp_repolish_clones(struct gfs2_rgrpd *rgd)
{
	struct gfs2_sbd *sdp = rgd->rd_sbd;
	unsigned int length = rgd->rd_ri.ri_length;
	unsigned int x;

	for (x = 0; x < length; x++) {
		struct gfs2_bitmap *bi = rgd->rd_bits + x;
		if (!bi->bi_clone)
			continue;
		memcpy(bi->bi_clone + bi->bi_offset,
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		       bi->bi_bh->b_data + bi->bi_offset, bi->bi_len);
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	}

	spin_lock(&sdp->sd_rindex_spin);
	rgd->rd_free_clone = rgd->rd_rg.rg_free;
	spin_unlock(&sdp->sd_rindex_spin);
}

/**
 * gfs2_alloc_get - get the struct gfs2_alloc structure for an inode
 * @ip: the incore GFS2 inode structure
 *
 * Returns: the struct gfs2_alloc
 */

struct gfs2_alloc *gfs2_alloc_get(struct gfs2_inode *ip)
{
	struct gfs2_alloc *al = &ip->i_alloc;

	/* FIXME: Should assert that the correct locks are held here... */
	memset(al, 0, sizeof(*al));
	return al;
}

/**
 * try_rgrp_fit - See if a given reservation will fit in a given RG
 * @rgd: the RG data
 * @al: the struct gfs2_alloc structure describing the reservation
 *
 * If there's room for the requested blocks to be allocated from the RG:
 *   Sets the $al_reserved_data field in @al.
 *   Sets the $al_reserved_meta field in @al.
 *   Sets the $al_rgd field in @al.
 *
 * Returns: 1 on success (it fits), 0 on failure (it doesn't fit)
 */

static int try_rgrp_fit(struct gfs2_rgrpd *rgd, struct gfs2_alloc *al)
{
	struct gfs2_sbd *sdp = rgd->rd_sbd;
	int ret = 0;

	spin_lock(&sdp->sd_rindex_spin);
	if (rgd->rd_free_clone >= al->al_requested) {
		al->al_rgd = rgd;
		ret = 1;
	}
	spin_unlock(&sdp->sd_rindex_spin);

	return ret;
}

/**
 * recent_rgrp_first - get first RG from "recent" list
 * @sdp: The GFS2 superblock
 * @rglast: address of the rgrp used last
 *
 * Returns: The first rgrp in the recent list
 */

static struct gfs2_rgrpd *recent_rgrp_first(struct gfs2_sbd *sdp,
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					    u64 rglast)
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{
	struct gfs2_rgrpd *rgd = NULL;

	spin_lock(&sdp->sd_rindex_spin);

	if (list_empty(&sdp->sd_rindex_recent_list))
		goto out;

	if (!rglast)
		goto first;

	list_for_each_entry(rgd, &sdp->sd_rindex_recent_list, rd_recent) {
		if (rgd->rd_ri.ri_addr == rglast)
			goto out;
	}

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	rgd = list_entry(sdp->sd_rindex_recent_list.next, struct gfs2_rgrpd,
			 rd_recent);
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	spin_unlock(&sdp->sd_rindex_spin);
	return rgd;
}

/**
 * recent_rgrp_next - get next RG from "recent" list
 * @cur_rgd: current rgrp
 * @remove:
 *
 * Returns: The next rgrp in the recent list
 */

static struct gfs2_rgrpd *recent_rgrp_next(struct gfs2_rgrpd *cur_rgd,
					   int remove)
{
	struct gfs2_sbd *sdp = cur_rgd->rd_sbd;
	struct list_head *head;
	struct gfs2_rgrpd *rgd;

	spin_lock(&sdp->sd_rindex_spin);

	head = &sdp->sd_rindex_recent_list;

	list_for_each_entry(rgd, head, rd_recent) {
		if (rgd == cur_rgd) {
			if (cur_rgd->rd_recent.next != head)
				rgd = list_entry(cur_rgd->rd_recent.next,
						 struct gfs2_rgrpd, rd_recent);
			else
				rgd = NULL;

			if (remove)
				list_del(&cur_rgd->rd_recent);

			goto out;
		}
	}

	rgd = NULL;
	if (!list_empty(head))
		rgd = list_entry(head->next, struct gfs2_rgrpd, rd_recent);

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	spin_unlock(&sdp->sd_rindex_spin);
	return rgd;
}

/**
 * recent_rgrp_add - add an RG to tail of "recent" list
 * @new_rgd: The rgrp to add
 *
 */

static void recent_rgrp_add(struct gfs2_rgrpd *new_rgd)
{
	struct gfs2_sbd *sdp = new_rgd->rd_sbd;
	struct gfs2_rgrpd *rgd;
	unsigned int count = 0;
	unsigned int max = sdp->sd_rgrps / gfs2_jindex_size(sdp);

	spin_lock(&sdp->sd_rindex_spin);

	list_for_each_entry(rgd, &sdp->sd_rindex_recent_list, rd_recent) {
		if (rgd == new_rgd)
			goto out;

		if (++count >= max)
			goto out;
	}
	list_add_tail(&new_rgd->rd_recent, &sdp->sd_rindex_recent_list);

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	spin_unlock(&sdp->sd_rindex_spin);
}

/**
 * forward_rgrp_get - get an rgrp to try next from full list
 * @sdp: The GFS2 superblock
 *
 * Returns: The rgrp to try next
 */

static struct gfs2_rgrpd *forward_rgrp_get(struct gfs2_sbd *sdp)
{
	struct gfs2_rgrpd *rgd;
	unsigned int journals = gfs2_jindex_size(sdp);
	unsigned int rg = 0, x;

	spin_lock(&sdp->sd_rindex_spin);

	rgd = sdp->sd_rindex_forward;
	if (!rgd) {
		if (sdp->sd_rgrps >= journals)
			rg = sdp->sd_rgrps * sdp->sd_jdesc->jd_jid / journals;

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		for (x = 0, rgd = gfs2_rgrpd_get_first(sdp); x < rg;
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		     x++, rgd = gfs2_rgrpd_get_next(rgd))
			/* Do Nothing */;

		sdp->sd_rindex_forward = rgd;
	}

	spin_unlock(&sdp->sd_rindex_spin);

	return rgd;
}

/**
 * forward_rgrp_set - set the forward rgrp pointer
 * @sdp: the filesystem
 * @rgd: The new forward rgrp
 *
 */

static void forward_rgrp_set(struct gfs2_sbd *sdp, struct gfs2_rgrpd *rgd)
{
	spin_lock(&sdp->sd_rindex_spin);
	sdp->sd_rindex_forward = rgd;
	spin_unlock(&sdp->sd_rindex_spin);
}

/**
 * get_local_rgrp - Choose and lock a rgrp for allocation
 * @ip: the inode to reserve space for
 * @rgp: the chosen and locked rgrp
 *
 * Try to acquire rgrp in way which avoids contending with others.
 *
 * Returns: errno
 */

static int get_local_rgrp(struct gfs2_inode *ip)
{
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	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
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	struct gfs2_rgrpd *rgd, *begin = NULL;
	struct gfs2_alloc *al = &ip->i_alloc;
	int flags = LM_FLAG_TRY;
	int skipped = 0;
	int loops = 0;
	int error;

	/* Try recently successful rgrps */

	rgd = recent_rgrp_first(sdp, ip->i_last_rg_alloc);

	while (rgd) {
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		error = gfs2_glock_nq_init(rgd->rd_gl, LM_ST_EXCLUSIVE, 
					   LM_FLAG_TRY, &al->al_rgd_gh);
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		switch (error) {
		case 0:
			if (try_rgrp_fit(rgd, al))
				goto out;
			gfs2_glock_dq_uninit(&al->al_rgd_gh);
			rgd = recent_rgrp_next(rgd, 1);
			break;

		case GLR_TRYFAILED:
			rgd = recent_rgrp_next(rgd, 0);
			break;

		default:
			return error;
		}
	}

	/* Go through full list of rgrps */

	begin = rgd = forward_rgrp_get(sdp);

	for (;;) {
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		error = gfs2_glock_nq_init(rgd->rd_gl, LM_ST_EXCLUSIVE, flags,
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					  &al->al_rgd_gh);
		switch (error) {
		case 0:
			if (try_rgrp_fit(rgd, al))
				goto out;
			gfs2_glock_dq_uninit(&al->al_rgd_gh);
			break;

		case GLR_TRYFAILED:
			skipped++;
			break;

		default:
			return error;
		}

		rgd = gfs2_rgrpd_get_next(rgd);
		if (!rgd)
			rgd = gfs2_rgrpd_get_first(sdp);

		if (rgd == begin) {
			if (++loops >= 2 || !skipped)
				return -ENOSPC;
			flags = 0;
		}
	}

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	ip->i_last_rg_alloc = rgd->rd_ri.ri_addr;

	if (begin) {
		recent_rgrp_add(rgd);
		rgd = gfs2_rgrpd_get_next(rgd);
		if (!rgd)
			rgd = gfs2_rgrpd_get_first(sdp);
		forward_rgrp_set(sdp, rgd);
	}

	return 0;
}

/**
 * gfs2_inplace_reserve_i - Reserve space in the filesystem
 * @ip: the inode to reserve space for
 *
 * Returns: errno
 */

int gfs2_inplace_reserve_i(struct gfs2_inode *ip, char *file, unsigned int line)
{
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	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
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	struct gfs2_alloc *al = &ip->i_alloc;
	int error;

	if (gfs2_assert_warn(sdp, al->al_requested))
		return -EINVAL;

	error = gfs2_rindex_hold(sdp, &al->al_ri_gh);
	if (error)
		return error;

	error = get_local_rgrp(ip);
	if (error) {
		gfs2_glock_dq_uninit(&al->al_ri_gh);
		return error;
	}

	al->al_file = file;
	al->al_line = line;

	return 0;
}

/**
 * gfs2_inplace_release - release an inplace reservation
 * @ip: the inode the reservation was taken out on
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